Folie à Deux
by seilleanmor
Summary: I came as (character A) and you came as (character B) and well, look at that, (character A/character B) is both of our OTP. A co-authored story between myself and ivyandtwine. Two shot.
1. Chapter 1

"I'm not asking you to dye your hair red and call me Mulder."

Richard Castle, _Close Encounters of the Murderous Kind_

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 **Folie à Deux**

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Smoothing her hands over the wig, Beckett tucks two fingers up underneath the mesh of it and scratches her fingernails against her scalp. It's already driving her insane and she can't stop touching it to be sure it's firmly in place, which only makes it shift and irritate some other part of her skin.

The elevator doors peel open and Kate snorts to disguise her little jump of horror, one hand pressed to her chest. Her fingers mess with the too-big lapel of her jacket and she steps out of the elevator car to peer at the severed head fixed to the wall opposite.

Beckett has actually seen a real life severed head before, and this one has the waxy skin and unfocused eyes of the victims she's visited on Lanie's slab. One of the girls she rode up with steps off the elevator behind Kate and immediately screams, a hand clutching at her own throat.

She must be one of Alexis' friends, and the boy with her wraps an arm around her shoulders and hustles her down the hallway, muttering something to himself that Kate doesn't quite catch. It means she's alone with the head though, and she peers closer.

Somehow her partner has even managed to make it smell disgusting. Not as bad as an actual decomposing person with the brain matter dripping from the severed base of the neck, but it's enough that Kate wrinkles her nose and comes in closer to try and catch the putrid smell again.

Right as she leans in the black maw opens wide, only sinew keeping the jawbone attached to the rest of the skull, and Castle's voice comes rumbling out. It makes her jerk in alarm and take a step backwards, curiously off balance in her flat shoes, and Kate swallows her yelp as her partner's best scary voice rings out like a doomsday toll.

It's directions to his home, first door down the hall on your left, and Kate covers her mouth with three fingers. She's alone in the hallway, and it's not like her smile is at all obscured by the half-hearted flit of her fingertips, but she's wary of letting anybody see.

And, well, she's in character. She has to be careful not to let this goofy man crack her careful scientist façade.

Following the directions the severed head gave, Kate makes her way to Castle's front door. Her stomach is a living, whiny thing inside and it chews at her, nerves making her shrug her shoulders in the enormous blazer. It's so silly, so irrational, but she is in costume. That first year she went for scary, but after she unhooked the puppet from her stomach she had just looked boring, like she hadn't bought into the party.

The year after that, Kate had snubbed her new boyfriend and gone to Castle's party with Lanie, the two of them dressed as Thing 1 and Thing 2. It was only a t-shirt, and Lanie was the one to find them, so all Beckett had to do was pull it on with her jeans.

This is the first year she's tried, put time and effort into her costume, and anticipation fizzes like Alka-Seltzer behind the wall of her sternum.

Just yesterday, she and Castle closed the Ghost Wranglers case, and the thrill of the solve still courses through her system. It was so much fun, and even though his constant and mostly unfounded theories about Apparition Americans were a niggling itch at the base of her skull, she's proud of them. How well they worked through it together, how much a great team they still are.

Since Serena Kaye, since Castle turned the insurance investigator down in favour of burgers with Kate, their relationship has been in tentative bloom. It feels like she's a green shoot, huddled close down in the shade, against the earth. And now for the first time, ready to turn her face towards the sun.

Exploring that house during the witching hour, the crackle of awareness down her spine had set Kate firmly on edge. She had teased and joked with him, and oh, God- climbed on him. It's made her giddy, excitement just at the thought of seeing the man who loves her spilling over from her heart in a cascade of lovely warmth. It settles like liquid need in her guts and Kate sucks a slow breath through her nose before she knocks on his front door.

She already knows that he's going to appreciate her costume. Honestly, she could dress as anything at all and he'd be overjoyed just that she's tried, but this? He's going to be delighted with her reference, and the thought of that pleased and dorky smile he gets when she does something nerdy had made her heart roll over in her chest. She'd been fussy with the details, picking out each individual element with care, and it's been driving him nuts that she won't give him even a single clue.

Her partner wrenches open the front door of his home with gusto, sending the air ruffling through the flop of his bangs so that his hair falls into his eyes. The party is a loud and pulsing thing behind him, but Kate's focus is entirely on Castle as he stoops low in a dramatic bow, speaking words of extravagant welcome. The moment he rakes his eyes over her costume though, he cuts himself off on a strangled noise and gapes at her.

His eyes travel a scalding path over her body, but Beckett doesn't appreciate his gaze like she so often does lately. Instead, she can't help but stare at his costume, and she sucks in a breath.

Castle is wearing a hideous tie, some floral patterned thing in a variety of shades that really ought not to be sharing such a small length of fabric. A packet of sunflower seeds pokes out from where his pocket square should be, and just underneath is his identification badge.

The same identification as her own, clipped to her lapel and flapping against her chest whenever she moves, only with a different signature and photograph.

 _Agent Mulder, FBI_ , his badge says and of course, of course, Kate is his partner.

Her pulse thunders at the base of her throat, panic clutching at her, and it's all she can do just to stare at him. The red wig brushes the angle of her jaw whenever she moves her head, the hair short and sleek, and Kate finds herself bracing for her partner to say something crude or annoying.

The suit jacket she bought is just a little bit too big, the shoulder pads obnoxiously large. Kate shrugs inside the blazer to shift the way it's sitting, but Castle's gaze is firmly caught on the black pencil skirt of her suit. It's the perfect blend of 90s FBI agent and a little sex appeal, and he finally jerks his head up to meet her eyes.

"Spooky," he breathes, not even smiling. Just staring, and one hand clenches into a fist and presses hard against his thigh.

"Castle," she says, careful not to let the seething froth of what the hell come spilling out while they're still here frozen in his doorway. "Are you dressed as Mulder?"

He grins, bouncing on the spot like a little boy, and he flicks a fingernail against the ID badge pinned to his lapel, sends it swinging up into her field of vision. "Yep! And you're Scully."

"I know who I am, Castle. You said you were dressing up as Captain America." She glares at him and folds her arms across her chest, waiting on some sort of explanation. He loves the show, she knows that - it's why she chose this costume in the first place - but she wasn't prepared for them to match.

It looks as if they've done it on purpose, as if they colluded together and came up with a couple's costume, and Kate grits her teeth in preparation for the teasing they'll endure tonight.

"I couldn't find a good enough shield at the last minute," he whines, scuffing the toe of his shoe across the floor and pushing his hands into his pockets. He's thicker than Mulder is, his shoulders more broad, but he somehow manages to look just like the gangly dork that a teenage Kate fell a little bit in love with. "And after our case this week, this seemed fitting. And easy. Why is it even a problem?"

"Because, Castle," she says slowly, as if she's explaining something very simple to a very young child. "Everyone is going to think that we planned this. It's a couple's costume!"

She's overreacting and she knows it. Her voice rises as she talks and by the end of her sentence she's shrill enough that several heads snap towards them, the focus of his guests pulled away from the party. She ignores them completely, her gaze firmly on her partner, and she watches the work of his throat as he swallows.

It's just a Halloween costume, but her brain is a frantic knot of concern over the connotations that this is going to have, and Beckett works two fingers against her temple to massage away the stress headache that's gestating there. People they know are here, their colleagues, and she absolutely does not need any more stares and snide little comments than they already receive at work.

"It'll be fine, Beckett," he says, his body sagging against the doorframe as if he's already accepted that the battle to convince her is over. He keeps fighting anyway, struggling up from the mud and the detritus to weaponise his furrowed brow and turn it towards her, his bottom lip swollen into a pout. "Most people know who we are and that we're just colleagues and friends, and I'm sure you'll let anyone else know if they're mistaken."

His face falls, and her heart flings itself against the wall of her chest. Sucking a breath through her teeth, Kate lets her eyes close for just a second so that she can calm herself. She never meant to wound him with her protesting, so Beckett shakes her head and musters a smile for her partner.

"Sorry, Castle, I didn't mean to-"

"It's fine Kate, it's just one night," he blurts out, reaching for her and curling his fingers around her wrist to tug her into the loft. "I'll pour you a drink; try to have fun. Don't worry about what other people think."

Kate presses her lips together, but it's not like she can change her costume now anyway. She nods once, and then she allows him to pull her inside his home. It makes him grin and she can't help the answering tug at the corners of her own mouth, turning her face away from him so that he won't see.

It gives her a chance to take in his loft, and she arches an eyebrow as she glances around the place. It looks incredible; he's gone all out, more than she's seen before, and her eyes are drawn in fifteen different directions at once.

A skeleton sits at the dining table, top hat impossibly jaunty on his skull and a bow tie loose around the top ridges of his vertebrae. There are jack-o'-lanterns everywhere, their carvings exquisite and intricate, and ghosts and monsters and really, every possible kind of decoration that she imagines must exist.

"Wow," she breathes, turning back to look at her partner. He's grinning, and when she meets his eyes he wriggles his shoulders and brushes a dangling cobweb out of their way so they can move towards the kitchen.

On top of the island, an actual bubbling cauldron sits pride of place, and Kate is so distracted by it that she doesn't notice the mechanical grim reaper by the refrigerator. His scythe moves up and down and snags in her wig, makes her yelp and duck out of the way.

"Sorry, sorry," Castle says, a hand between her shoulder blades to steer her out of the path of the zombie horde overtaking his loft. Once they make it to the open space in the middle of the kitchen he drops his hand from her back, ducking in close to see her. "Alright?"

"Of course," she smiles, peeking past his shoulder at the incredible mess of spider webs carefully strung over almost every piece of furniture. "Castle, this is incredible. I knew you loved Halloween, but this. . ."

He follows her line of sight, taking in the spill of people and noise in his home, and when he comes back to her pride makes his face smoother at the edges, his lips thinning around his smile. "It's been a difficult year. But I think we're getting back on track again, finding our footing, so I wanted to do something fun for everyone."

"Well you succeeded," she laughs. It's all so impressive, and her anxiety about their matching costumes drains slowly away in favour of childish joy. When she was a kid Kate loved Halloween; trick or treating, picking out the pumpkins to carve with her parents, and the crisp edge to the world that rolled in with fall. She would stomp on the crunchiest leaves, always several paces behind her parents to make sure that she got them all, and the yearning to stroll hand in hand with her partner and crunch the leaves in the park settles in her chest.

It's not urgent, not the way everything has felt for so much of this year. Just a slow, lazy want that she's happy to let alone for a while. Not too long, but Kate is so glad to find calm working its easy way through her system.

Martha and Alexis come into the kitchen and Kate opens her mouth to greet them, make small talk about their costumes. Before she gets a single word out, Castle is steering her towards the dining table where all the drinks are laid out. His hand is low down at her back now, right in the curve where her hips flare out, and she grits her teeth through the shudder.

"Not really helping the 'we're not a couple' thing here, Castle," she mutters, but there's no inclination to shift away from him. Those six points of contact - five fingertips and the heel of his palm - have heat spreading through her system, her blood pulsing, and she has to force herself not to list into him.

He ignores her words completely, choosing instead to pull his hand away from her body so that he can pour her a drink. The punch bowl has actual smoke rolling across the surface of the liquid, dry ice she assumes, and her fascination is a welcome distraction from how she immediately misses his touch.

Handing her the glass, he pours one for himself and clinks his goblet against hers, waits for her to take a sip. "You're not wearing heels."

"Well, uh. . .Scully is short. And I'm not. But I figured I should get as close as possible." She lifts one shoulder in a shrug and catches her lip between her teeth, her eyes dropping to her own shoes. She feels weird to be dressed in something so close to what she might normally wear for work, but without her power heels, and she lifts up on tiptoe in her flats for just a moment.

"I like it. The height difference."

Her eyes snap to his immediately. He's staring down at her and Kate presses her lips together, feels clammy and juvenile all of the sudden.

When they do this, he'll cradle her in his arms. Her head will fit perfectly in that curve between neck and shoulder, her body pressing in close as his arms come around her and-

Breaking away from his gaze, Kate sucks in a shaky breath and takes another sip of the drink he poured for her. It's not exactly like she's looking to get drunk tonight, but a little liquid courage won't hurt.

Even if that liquid is green, and curiously viscous. It's strong, the burn of the alcohol making her shudder, but a sweetness lingers in her mouth after she swallows it down. Just what she needed, and she nods at him in approval. It makes him smile and he wraps his free hand around her elbow.

"Come on, Beckett," he says, tugging her away from the drinks. "I want to show you some of the new decorations I got this year. Oh! There's even an alien here somewhere, we've definitely gotta take a photo with him."

She laughs, loud and bright and her eyes creasing up at the corners, and she shakes her head at him. Bending her arm, she traps his fingers in the crook of her elbow and he wiggles them, shooting her a grin as he drags her over to a disturbingly realistic gravestone. It's got a zombie hand peeking out of some fake dirt, and joy fills her body to have him so eager and close.

"Oh my God, are you two dressed as Mulder and Scully? Together?"

They turn and he drops his hand from her elbow, hurriedly stuffing it into the pocket of his slacks. The round, delighted faces of Ryan and Jenny peer at them in scrutiny and Kate feels the lick of embarrassment in her cheeks, trailing along the slope of her neck.

"No," she says, right as her partner gives the opposite answer, and she narrows her eyes at him. "Not together. It was just a coincidence, because someone was too lazy to bother with his original idea."

"That is so adorable," Jenny says, her hands clasped and pressed against her heart. She's wearing a green dress, the bottom of it jagged, and her shoes have gigantic pom poms on the end of the toes. With the delicate wings at her back and her hair elaborately swept up, she makes a perfect Tinkerbell.

Ryan, to his credit, is managing to hold on to some of his manliness while wearing what is essentially tights and a tunic. His hat is magnificent, but Castle is grumbling and shaking his head. "You guys didn't even try to be a little bit scary? Come on. It's Halloween."

"Neither did you two," Kevin fires right back, sliding an arm low around his fiancée's waist. "Beckett, you're like one degree away from what you wear every single day."

"Hey, I love The X Files," Jenny says, sending Kate a reassuring smile, and Beckett nods her head at Ryan's fiancée.

"Me too," she agrees, smiling back at Jenny, because at least this is something she can talk about that doesn't involve her partner, or their complicated relationship.

The four of them get sucked into a discussion of their favourite episodes, and how they found the second movie a little bit lackluster, and Kate finds herself laughing. Enjoying the conversation, not even minding when Ryan notes that Beckett and Castle are really very similar to Scully and Mulder.

She only rolls her eyes, makes a joke about being glad that aliens haven't visited Earth. That of course sets Castle into a tailspin, reminding her of that case they worked this time last year and how they were actually abducted, Kate. Alexis appears then, starts talking about physics and probability and how sure they can be, really, that other life forms don't exist out there.

After a few minutes Kate excuses herself and ducks into Castle's study. It's quieter in here, even with the bookshelf walls, and she leaves the lights off. Skimming her fingers along the titles on his shelves, Kate lifts a hand to her hair only to realise that she can't scrape her fingers through it.

She's happy to be here, surrounded by warmth and family and laughter. Happy to be alive at all, and she anchors her free-floating hand against her chest. Her fingertips work against the knot of scar tissue between her breasts and she sinks to lean against the back of Castle's desk.

This summer, she spent so much time alone in the quiet of the cabin, and now she finds herself overwhelmed with the pulse of life that is this city. Glancing around the room, Kate can't help her soft chuckle at the decorations her partner has put up in here.

For only him to see, and now her too.

The door cracks open and Castle peeks inside, grinning when he catches sight of her. He comes all the way into the room and heads to prop himself up beside her against the desk. "Hey. Too many people?"

"Something like that." She shrugs, fighting the urge to lean her head against his shoulder, but it's late and they're dressed as the couple that Kate once held up as a paragon of true and pure love. Kate lets herself rest, her cheek meeting Castle's shoulder, and he turns his head to dust his lips to her crown like it's a reflex.

"I really am sorry," he says quietly, and Kate picks her head up again to frown at him. "I didn't mean to embarrass you. I actually thought it might make you smile. Because he and I are so alike, you know?"

She nods at him, shifting a couple of inches away so that she can see his whole face and not just one huge, unblinking eye and the shard of a smile. "I do know. It's the perfect costume for you. For us, really. Partners who are constantly winding up in ridiculous situations?"

"Right," he laughs, a cute little huff of breath, and he tugs the sunflower seeds out of his pocket. "Want one?"

"No thanks."

"Yeah," he scrunches his face up and sets the packet on the desk behind himself. "Me neither. I don't really like them."

That makes her laugh out loud and she twists on the desk, a knee coming up and nudging against his thigh. "You don't have to eat them just because of the costume. And by the way, the party is fantastic. I'm not in here because I wasn't enjoying it."

"Just needed a little time to yourself," he nods, bumping his elbow into her bicep. "Want me to leave you alone?"

"You should probably get out there and host, right?" she asks, staring at her own feet as she drums her heel against the back of the desk.

Castle's hand falls to her knee and squeezes, sending stillness through her like the slow pour of cement, and it's all she can do to stare at him.

"That's not what I asked. Mother and Alexis are doing a fine job, and honestly Beckett? It's so busy out there that I bet you and I could stay in here and watch a movie all night and no one would even notice that we were gone."

"Not tonight," Kate shakes her head, covering his hand with her own. She nudges her fingers into the spaces between his, a backwards hand hold. "Castle, I'd love to do a horror movie marathon with you, but not with hundreds of people outside the door listening to your unmanly screams."

His eyes widen, and too late Kate realises what she's said.

Yeah, well. . .she doesn't want anybody listening outside the door to that, either. So she won't take it back.

"Wanna come over tomorrow?" he offers, flipping his hand in hers so that he can hold it properly. It's not the first time she's held his hand, but they don't allow themselves to do this, and pleasure zips down her spine at the simple contact.

"I'd love to," she smiles, drumming both feet against the desk now. Something about the way he smiles at her makes her feel girlish and smitten, and Kate has to turn her face away so that he doesn't see the spill of adoration. "I'll bring the snacks. But for now, we should get back out there. Before we start any ridiculous rumours."

Kate hops down from the desk and tugs him up with her grip on his hand, the way his body looms over hers making her swallow. For a moment, she's arrested by the urge to crash against the wall of his chest and her breath comes rattling and laboured.

The cobwebs attached to his ceiling hang down between them and Kate wrinkles her nose, steps just slightly to the side so that she can see him without the spidery mess of gossamer getting in her face.

"You really committed to the decoration, huh?" she smirks, flicking a finger against a rubbery spider that sits on top of Castle's desk. It wobbles, its body distorting for a moment, and then it bounces right back into its cartoon shape.

"It inspires me," Castle says, glancing around himself to take in the decor. It's more subtle in here, decidedly spider-themed, and when he turns his face back to hers he's grinning and wiggling his eyebrows. "Gives me a little kick of adrenaline, you know? Gets the words flowing."

"Hey, I'm not judging," Kate says, showing him her palms, but she can't seem to get control of the amusement that quirks one corner of her mouth. "I just feel pretty sorry for you. The clean up's going to be a nightmare."

His mouth opens and then closes again, a tiny squeak coming out, and then his whole face scrunches up into a frown at her. "You're coming over tomorrow, Beckett. Be careful, or you might get roped into helping me."

"Oh no, this is your mess," Kate says firmly, folding her arms across her chest. "And why have you got the cobwebs dangling so low everywhere? You're a tall guy, isn't it bothering you to have them in your face?"

"I thought they were kinda like Halloween's version of mistletoe," he grins, reaching up to bat at the cobweb that hangs down between them. "I was mostly hoping it might nudge Lanie and Javier to just reconcile, already."

The two of them only parted ways a couple of days ago and Kate snorts at the feeble excuse, shaking her head at him. "We both know that's not true, Castle. It's not even a thing. What were you going to do, put signs up? Please treat the spiderwebs like mistletoe."

"Alright fine," he huffs, shoving his hands into his pockets again. "So it only just occurred to me right now, with it between us like that."

Oh.

Wow.

Castle was thinking about kissing her.

It's not really a surprise, not if he thinks about it half as much as she does, but it still makes her heart do a funny little flip. Her partner wants to kiss her, wants it enough that it plays on his mind all the time, whenever he looks at her.

"It doesn't- I don't mean- we don't have to," he's spluttering now, his shoulders up next to his ears. "It's just because of who we're dressed as. They're- what's the phrase you used? I ship them?"

"Yeah," she laughs, so grateful for the easy way he sends a crack splintering through the shell of panic that descends over her. "I ship them too. Since I was a teenager, really. I remember watching the New Year's episode, when I had just turned twenty. I tried so hard to pretend that I wasn't that invested anymore, and then they shared that kiss and I almost fell off the couch."

That makes Castle grin and he plays his fingers against the bottom of his tie, the goofy pattern and the strangled pulse of his neck making her laugh all over again. "Those are the best kinds of kisses. The ones with years worth of build up."

Her throat goes suddenly dry and Kate swallows, staring at him. "Yeah. It was- I was still hurting so much, Castle. Still reeling, really. But that show was like a bright spot in my grief. For an hour each week I could put it away and focus on the drama and the romance. And the aliens."

"I had no idea it matters so much to you," he says, fingers flexing and relaxing uselessly at his side. "Temptation Lane, sure, but this show?"

"I got invested," she laughs, determined to be the one to break the tension this time. She wasn't looking for him to shoulder her grief. Not tonight, anyway, with his Halloween playlist rolling back around to the classics and everyone yelling out the Time Warp lyrics from his living room.

Castle arches one eyebrow at her and smiles, swathes of shadow licking at one side of his face. "I did too. Not just in them."

"No?"

"No," he says firmly, and she watches in something close to wonder as he gathers his courage, screws it to the sticking place. "I'm invested in us, Kate Beckett. You and me. And I hope it doesn't take seven years, but trust me when I say that when we have our moment, you'll do more than just fall off the couch."

Heart pounding, Kate stares up at her partner and her lips part, her tongue a dry and useless thing inside her mouth. All of the reasons they shouldn't do this roll over her in one great tide of uproar, but she shrugs off the fluttering ghost-things and nods her head once.

Castle is watching her, panic flickering across his face, and his whole body sways. Tucking two fingers underneath the wig, Kate eases it off her head and dumps it on the desk beside them.

It looks hideous there, grotesque, and Castle huffs a laugh and picks it up to wear on his fist, tucking his thumb underneath his fingers and moving it like a mouth. "I looked a lot prettier on you, Detective."

"I"m trying to be serious here," she grumbles, but his goofiness gives her a chance to unwind her hair from its braid and shake it out over her shoulders, unclip her name badge. She wants to do this as herself. Not as Dana Scully.

Reaching for her partner, Kate takes his ID badge too and drops it to the desk with hers. He's gaping at her now, the fist still wearing the wig limp and held against his chest. Kate unfastens his tie and feeds it through his collar, letting it pool on the desk before she takes her wig back from her partner.

He unfastens his top three buttons himself, tilting his head to work his neck now that he's got room. Like this, it could be any day with the two of them, but it's not. It's not any day.

"Castle. There were so many times I found myself yelling at the TV because they couldn't just be honest with each other. And that's fun, on a show. It's exciting and it keeps you captivated. But in real life, it just hurts. And I don't want that to happen to us. I don't want to wait that long for our moment."

"Kate?" he gets out, and then she lifts up onto the tips of her toes and winds an arm around his neck. Her other hand fists in his lapel, and Kate kisses him. The touch of her lips against his is firm and confident and she clings to him even as he shivers and stumbles a step backwards.

It takes only a moment, and then he comes alive beneath her. Castle's hands cup her jaw, angling her head so that he can slick his tongue past the seam of her lips and into the wet heat of her mouth. She lets him loom over her, lets him push her up against the desk, and then his hands are at her hips and lifting, guiding her to sit on the surface.

She doesn't want to let herself go, not with everyone they love right outside the door, so Kate gentles him with the sift of her fingers through his hair and the slow again and again press of her closed mouth to his. When she eventually manages to break away, his forehead meets hers and he smiles.

"The world didn't end."

"Didn't you hear?" she hums, stealing another kiss from him. "That's not until December 21st. We've got a couple of months yet."

"Oh," he says, pulling back to look at her. Castle tucks the spill of her hair back out of her face and skims his thumb along the swell of her bottom lip, his smile wider than she's ever seen. "Good."

And then he's kissing her again.

* * *

I came as (character A) and you came as (character B) and well, look at that, (character A/character B) is both of our otps…strange…we should do something about that….like make out

* * *

 **seilleanmor:** Alex is a lovely and radiant human being, and a very dear friend of mine. I _love_ her writing, and so it was a pleasure and a privilege to work with her for this story. There's a part two coming tomorrow, of their movie night, so be on the lookout for that.

 **ivyandtwines:** bean is amazing and so great to work with, and I'm so grateful to her for letting me collab with her. It's ridiculous how clever she is and she's has taught me so much even from this short fic 3


	2. Chapter 2

**Folie à Deux**

* * *

Kate wriggles her toes and relaxes into the cavernous warmth of the couch in Castle's office, her legs tucked up all snug beneath the blanket he found. It's huge, a faux fur that tickles the backs of her fingers, but she's glad for the warmth. Winter is beginning to roll in to their city now, and the cold presses its face up against the windows of the loft and peers inside.

Her partner is making popcorn, and the buttery smell drifts through from the kitchen. It reminds her of movie theatres, of clammy handholds and nervous conversation, and she huffs a breath of laughter. They're not that, not kids on their first proper date, even if the goofy tilt of his mouth makes her blush like an adolescent.

Body loose and languid, Kate is comfortable in her yoga pants and a huge purple sweater. It's a step down from last night's costume, but she's content to relax in Castle's home. He'd been delighted when he answered the door to her earlier tonight, reeling her in with a fist in the material at either side of her hips. He had kissed her hello, a soft and fleeting thing, and then he had tugged away enough to whisper to her.

 _I'_ _ve been waiting forever to do that_.

The anticipation of cuddling up with her partner for their horror movie marathon makes her giddy and she hides a grin against her palm. Kate's not looking to play it cool tonight; she'll hold his his hand through the scary parts and bury her face against his chest to let him feel macho.

Since the party last night, she's barely been able to stop smiling, and her cheeks ache with the force of her bubbling joy. All day, little bursts of heat have rippled through her whenever she has allowed herself to think about last night.

Beckett rushed through her paperwork this afternoon, eager to leave as early as she could get away with, and the moment she scrawled her last signature down she escaped the precinct. She almost wanted to go straight to the loft, her eagerness to see her partner a living force, but she headed home and changed into something comfy first. Took a shower, and tried to let the water sluice away how viscerally she missed him.

He doesn't always come to the precinct on days when they don't have an active case, and today his absence was a sentient thing in her belly that chewed away at her. They texted back and forth all day, each hamming it up to keep the other entertained. He spent his day cleaning the loft and while she protested last night, helping him deal with the aftermath of the party would have been infinitely preferable to being trapped in the precinct. He sent her videos of him lip-synching to the Halloween playlist while he packed the more durable decorations away in a box and she had laughed out loud, the boys' heads snapping up to stare at her.

There were pictures too, trash bags collecting into one lumpy, garbage-sweet creature and a mountain of dishes to wash. Castle had a lot of food leftover and he had run it down to the homeless shelter a few blocks over from his place. Warmth floods her at the thought, how good her partner is, and she turns her head even though it's impossible to see him from this angle.

He sent her a photograph of the spiderweb they kissed underneath, a little caption attached and telling her that he plans to leave it there a while, and sure enough it still hangs just in front of his desk. Biting her lip, Kate draws the blanket up to her neck and lets the slow smile stretch her mouth.

They kissed.

She kissed him, and she didn't slam up against her self-built wall and come away bruised.

They didn't let themselves linger in his office for very long, not wanting to make any of the guests suspicious, but the first thing that Lanie noticed when she bumped into Kate was the crooked sit of her wig. Beckett laughed it off, fumbled some excuse about her scalp itching, but she's not sure she can hide this from her friend for very long. Not sure that she wants to.

She'll have to talk to Castle first, about so many things, and then they'll have to decide the best way to reveal their togetherness and to whom. For now though, she just wants to enjoy the movie marathon and relish in the new, green bloom of their budding relationship.

Her heart is a timid, fluttering thing in her chest, and Kate is alarmed to find herself missing him after only a handful of minutes apart. She offered to help, but Castle had insisted that she stay on the couch and get comfortable, that he would be the one to get their snacks ready. Kate had rolled her eyes, but the kiss he had brushed to the corner of her mouth had sent a cascade of giddiness through her belly and she had disappeared into his study to make a nest on the couch.

Castle has left a few decorations around the loft in deference to their plans tonight; spiders still lurk in the dusty corners of his office, and all of the biggest figurines are standing proud in his living room. There's a stack of horror movies on his desk and Kate skims the titles as she waits for him to come back. Some are excellent choices, some. . .not so much. Watching B-grade horror movies can be just as fun as watching the classics though, especially with the melodramatic terror she's anticipating from her partner.

He materialises then, his hands full of various bowls and dishes, and he's quick to set them down on his desk. Besides the popcorn, there's a bowl of Halloween candy that managed to escape the clutches of the trick or treaters. His daughter made mummys from Nutter Butters dipped in candy melts, candy eyeballs stuck on the front, and Castle passes the plate of those over to Kate.

"I gave everything else to the food bank, but I noticed that you ate about seventeen of these last night, so I kept them just for you."

"Hey," she huffs, setting the plate on the windowsill behind the couch so that she doesn't end up dropping the cookies all over herself. "They're moreish. And I'm sure I didn't eat seventeen."

He shrugs at her, one corner of his mouth tugged up in a wry little grin, and he sets down the final plate. Castle made ghosts from strawberries, dipping them in white chocolate and then piping a horrified little face onto each one, and he pops one into his mouth as he comes to sit beside Kate.

Castle brings the popcorn bowl with him and the smell wafts in hot curls beneath Kate's nose. She lunges for the bowl, eager to dive in while it's still warm and buttery goodness, but he slaps her hand away. Irritation bubbles up inside for half a second, but he looks so earnest that her heart softens and she aches to slide her arms around his neck and draw him down to her.

"Can't eat the popcorn until the movie is on, Beckett."

Narrowing her eyes at him, Kate huffs and gestures for him to pick a movie from the selection. If he's not sharing the popcorn, she's not sharing her blanket, and she tucks it in tighter around herself.

"You have any preferences?" he asks, darting a glance at her as he shuffles through their shortlisted films.

"Maybe something not too scary to start with? I don't want you jumping and spilling popcorn all over me," she smirks, arching an eyebrow at him and stealing a strawberry from the plate to pop into her mouth.

"The Sixth Sense? Misery? IT?"

"IT?" she cries out, kicking a clumsy foot in his direction. "Castle, no. No clowns."

A shudder rattles through her at the thought of that infamous horror, how watching the movie at a sleepover when she was twelve made her cautious of clowns in general. Every time she came across one from then, even if it seemed harmless, she had worried that it would transform into the character with the sharp teeth and the balloons full of blood.

"Oh, are you scared of clowns?" he teases, wiggling his eyebrows and grinning at her. His eyes are alight with this newly revealed information and Kate scowls, folding her arms across her chest.

"No. Not scared. I just- I'm not a big fan, okay?"

He shows her his palms, and then he moves IT out of the pile and holds up two options for her. "Okay. No clowns. Pick one."

"The Sixth Sense," she decides. It's a movie that's creepy, but not too much so, one that had impressed her with its clever twist when she first watched years ago.

Castle slides the disk into the DVD player and comes back to sit beside her, moving the popcorn bowl from the couch cushion to the end table so that he can make himself comfortable. He tugs on the edge of her blanket and she clings tight to it, scowling at him.

"Kaaate," he whines, coming in close and nuzzling his nose against her cheekbone. "Share. Please."

"You wouldn't let me have popcorn," she huffs at him, but Kate lets go of the edge of the blanket.

Her partner tucks himself underneath and hooks an arm around her legs, hauling them until she's half draped over his lap. He shoots her a glance from the corner of his eye, and Kate leans in to the warmth of his arm and rests her cheek to his bicep in silent permission. Castle's hand settles at her shin, thumb running over the fabric of her leggings.

Skimming her hand up the width of his torso, Kate curls her fingers around the back of his neck and tugs his head down to hers. Her kiss is lazy and winding, the crackle of lust that flares between them making her ache for more.

Movie first, and Kate presses her thighs together and breaks away from Castle's mouth. He makes a pitiful little noise of distress, but he presses play on the remote and reaches for the popcorn bowl from the end table, settling it in his lap and gesturing for her to dig in.

Kate settles against her partner again, reaching for the popcorn and chewing on a few pieces. The work of her jaw against Castle's arm makes him smile and he kisses the crown of her head as the movie begins.

The popcorn disappears within the first fifteen minutes of the movie and it frees her hand up to tangle her fingers with Castle's. Her thumb sweeps back and forth at the underside of his wrist, where his skin is warm and soft, and whenever something in the movie alarms him he squeezes her hand.

They snack throughout the rest, Castle busying himself with the Halloween candy to let Kate have the strawberries and the Nutter Butters. She's trying not to eat them all, but he did save them especially for her so she's not feeling too guilty.

Castle comments throughout, telling her that he saw the twist coming when he first watched. It makes her snort and push her knuckle hard into the soft spot underneath his ribs until he squirms and admits that he didn't, that he had been amazed just as she was.

They stay pressed close, his hand only migrating from her leg when he reaches for more candy, and his touch settles in her guts like liquid heat, like need. She wants to finish their marathon, but she also wants to slide her knee over his lap and sink down right here on the couch.

After the movie ends she chooses Scream to watch next, another favourite from her teenage years, and they chat about how Wes Craven made this movie so very clever. It's a perfect mix of scary and funny, parodying other slasher films while still having an excellent twist.

Drew Barrymore pops up on their screen, interrogated by the creepy voice on the phone, and the action begins. Castle is tense beneath her as it picks up and Kate hides her smile against his arm. It's cute, the little jolts that zip through him, his grip on her calf growing tighter as the movie becomes more intense.

Kate's not usually one to jump at horror movies, but when the first big scare comes Castle yelps and jerks hard beneath her and she finds herself jolting in alarm that's half at the movie, half at him. Laughing, she slides her fingers slowly around his back and digs them into his side in jest.

"Hey, don't laugh, it's scary," he whines at her, but he catches her wandering fingers and squeezes them, trapping them there.

By the time they make it onto their third movie of the evening, her need has given way to lazy contentment. Kate has slid further and further into the couch and both Castle's arms are around her now, her body pillowed against him.

Last night ran late, the spark of a shared secret making her haunt Castle's side until almost all of the other guests had left the party, and she's paying for it now. Her eyes are gritty and she closes them entirely, rests her head against Castle's chest.

His fingers card through her hair, a little clumsy, and he snags in a knot. It makes her hiss and his lips come to the crown of her head again, his wide palm splayed out against the side of her skull. "Sorry. Didn't mean to hurt you."

Rubbing her face against his chest, Kate lets the tip of her nose press against his sternum in forgiveness and she curls up tighter. One arm is around her shoulders like a felled limb, but the warm weight of it is only serving to make her drowsier.

"This is kind of weird," he whispers to her as the movie plays out in front of them. Kate stiffens, horrified that she's gotten too comfortable, but his fingers land at the ball of her shoulder and squeeze. "Good weird, Beckett. The kind of weird that I can't wait to become our normal."

"Yeah," she hums.

"I've wanted to do this for so long," he admits, fingers working their way inside the collar of her sweater now and feathering out across her skin. "Just curl up with you. Be lazy. Get to. . .to hold you."

Kate works her way out from underneath the weight of his arm and pulls back enough to see his face. He's a little rumpled, prickling regrowth scattered along the edge of his jaw, and Kate lets three fingers come to his cheek to keep him in place.

Leaning in, she touches her lips to his in a shadow of a kiss. It's late, and they're both tired, and she doesn't want their first time to be tacked on to the end of movie night. She's careful not to stoke the embers of yearning in her stomach, doesn't slide her tongue past the seam of his lips like she aches to.

"I've wanted it too," she says when she breaks apart from him, and his breath comes in a great puff of relief against her cheek.

He smiles, his whole face crinkling up with boyish delight, and he nudges on her shoulder until she lays back down, her cheek against his chest. "Let's finish the movie, Kate."

Silence of the Lambs is a slow burn, and Kate finds herself dozing in and out of paying attention. She hears snatches of dialogue, her partner muttering along with the most famous parts, and then suddenly the credits are rolling.

Stretching, Kate sits up and frowns at Castle, rubbing a hand against her cheek. "I fell asleep on you?"

"Little bit, yeah," he laughs, reaching for her and trying to draw her back down to him. She feels like she's wading through the fog of sleep still and she shrugs off his touch, scrapes a hand over her face. "It's okay though. Kinda cute, actually. And impressive that you can sleep through a horror movie."

"Guess I was really tired," she hums, drawing her legs up and tucking her toes underneath his thighs. "I should head home."

Castle's hand drifts against the back of her head, his fingertips flirting with the ends of her hair, and his thumb smoothes over her earlobe. "You don't have to. You could. . .come to bed."

"Castle, I don't-"

"Just for sleep," he clarifies, tucking her hair back out of her face now. "I know things are moving fast, Kate. We don't have to do anything if you're not ready. To tell you the truth, I'm not sure I'm ready either. But I don't want to say goodbye."

Lifting her chin, Kate seeks his mouth and smudges a drowsy kiss against his lips, her fingers curled around his ear. "I don't want to either. I can stay. Sounds kinda nice, just to sleep."

"It's like Requiem," he says, stealing another kiss from her. "Except I'm hoping I won't get abducted by aliens. And I'm pretty sure you're not pregnant."

"Castle," she yelps, swatting at his chest to distract him from the pink bloom of embarrassment in her cheeks and along the column of her neck. "No, I'm not pregnant. Jeez."

He laughs, keeps her in place with both hands at her cheeks so that he can kiss her forehead. "Just the characters, Beckett. I'm only teasing. But come on, bed. You look exhausted."

"Thanks," she huffs, but she lets him pull her up from the couch and tangle their fingers together, leading her into his bedroom.

Kate hasn't ever been in here before, was careful not to even peek through the gaps in the bookshelves when she stayed here back when her apartment exploded. She hesitates in the threshold now and Castle gets pulled short by the grip of their hands. He turns back to look at her and she offers him a smile and a little nod, lets him take his hand back while she scans his bedroom.

It's not as nerdy as she was anticipating. She thought he'd have more gadgets, or a Star Wars bedspread, but his room is tastefully done in earth tones that make her want to stretch out across his sheets.

"Do you want to borrow a shirt? I might have some sweatpants too, but they'll probably drown you," he says from the dresser, a drawer pulled open. Castle rifles through it, a frown crinkling the stretch of skin between his eyebrows, and Kate crosses his room.

Laying a palm over his shoulder blade, she stretches up onto tiptoe to prop her chin on his shoulder and peek into the belly of the drawer with him. "I'm okay like this. My leggings are comfy."

"But you- are you okay sleeping in what you're wearing and then going home in that tomorrow?"

"I'll have to leave early," she says quietly, turning her head to dust a kiss to his cheekbone before he can even start to lament that. "And I'll go home and shower, change clothes. It'll be fine."

He shrugs, jostling her from his shoulder, and he turns around to see her instead. "Okay. If you're sure."

"I'm sure."

"Why don't you take first turn in the bathroom while I change, then?"

She kisses him before she goes, one hand at the back of his neck and the other hooked in the collar of his shirt. He tastes like candy and she hums, stepping in closer until the entire length of her body is flush with his.

His tongue sweeps through her mouth with devastating precision and she clings tight to him, has to break away from their kiss with a gasp. Thighs quivering, Kate cards a hand through her hair and rests her forehead against his chin. "Wow."

"I love kissing you," he says, fingers flirting with the ridge of her spine, and Kate has to force herself to step away.

"Me, too," she says, chin ducked so that she doesn't have to meet the rich heat of lust all over his face. "There a toothbrush in the bathroom?"

"Oh, yeah, there's one in the cabinet."

She nods, and then Beckett heads away from him. She uses the bathroom and then she stands in front of the sink, raking her eyes over her reflection. There are purple shadows underneath her eyes and her hair is all rumpled on one side from laying against Castle's knit sweater, but she looks good. Smiling back at her is a soft and happy person she's excited to get to know better.

A knock startles her and she pulls the bathroom door open to see her partner, smoothing a self conscious hand over her hair. "Hey."

"Hi," he grins, holding a bottle and a package of cotton pads out to her. "This is Alexis' makeup remover. I thought you might need some."

"Thanks," she says, taking everything from him and holding it against her chest. "Where is she, by the way? And your mom."

For a moment he can't even look at her, the entire left side of his face tugging up in sheepishness, and then he quirks a smile and tucks his hands into the pockets of his pajama pants. "I told them to make themselves scarce. That I wanted the house to myself tonight."

"Castle," she gasps, wishing her hands weren't full so that she could swat at him. "It's their home. Please don't kick them out because of me."

"Well, I thought that we might. . .you know, this evening."

"Have sex?" she says flatly, careful not to let the eruption of joy and nerves and disbelief unspool across her face.

He gulps, but he does manage to drag his eyes up to meet hers. "Yes. And I didn't really want them overhearing that."

"Me neither," she admits, glad to find that she isn't blushing anymore. They're adults, and he's her best friend. So yes, the thought of sex with Castle is a little strange, but she's not ashamed. Not embarrassed.

"Take your makeup off, Kate," he says, leaning in to kiss her forehead.

In the mirror, she watches Castle busy himself with something on his iPad as she cleans her face, brushes her teeth. He's very carefully not watching her, and it makes her heart pour in slow tenderness through the gaps in her ribcage.

"All yours," she says when she comes out of the bathroom, touching her thumb to the corner of his lips in greeting.

He closes the door and she wiggles her shoulders, huffs a breath through her nose. She's woken up next to him a couple of times, but they've never done the falling asleep part before and she's nervous. Kate wipes her palms off on her thighs and stands at the foot of his bed, frowning.

One of the nightstands has a glass of water and a book, and the other is empty aside from a lamp, so she chooses the sparser side and climbs beneath the sheets. There's an absolute mountain of pillows and Kate props herself up against the headboard to wait for him, the rise of her knees making a gap in the comforter so that cold air creeps inside.

When Castle comes out of the bathroom he stumbles to see her there. He covers it pretty smoothly, carries on around the bed to his side, but she catches the way his entire body slams to a halt and it makes her brave, makes her calm.

"Did I pick the right side?" she asks once he's settled and he laughs, darts in to kiss her mouth.

"You did. But it wouldn't have mattered. You can have whichever side you want, if it means I get to be in bed with you."

That makes her smile and she waits for him to lay down, dumping a couple of her pillows on the chair next to the bed before she joins him. Nose to nose, she reaches a hand up between their bodies and settles two fingers at his chin.

Kate kisses him, her fingers sifting through his hair, and then she turns over to put her back to him. One arm bands around her waist and he draws her across the sheets until she's tucked in close against the cove of his body.

A palm sneaks up underneath her shirt and splays at the bare skin of her stomach, his thumb brushing back and forth just below her belly button. It makes her feel drowsy and catlike and she sighs. Castle sweeps her hair out of his way so that he can kiss the nape of her neck, the length of his body warm and delicious.

"Sweet dreams," he whispers, and Kate shifts to get a little more comfortable in his arms. "Dana."


End file.
